Field of the Invention
The present disclosure relates to new anti-reflective coating formulations, methods of using the same, and microelectronic structures formed therefrom.
Description of Related Art
Bottom anti-reflective coatings are generally classified as either dry etch or developer-soluble. Dry-etch bottom anti-reflective coatings are well known, and are either thermoplastic materials that are applied in a certain solvent and are not soluble in the photoresist solvent, or are thermosets that are crosslinked and thus rendered insoluble in the photoresist solvent. Developer-soluble bottom anti-reflective coatings are classified as non-photosensitive (isotropic development) or photosensitive (anisotropic development). Non-photosensitive, developer-soluble bottom anti-reflective coatings may be thermoplastic materials that are applied in a certain solvent and are not soluble in the photoresist solvent but have acid groups that render the polymer soluble in base developer. Non-photosensitive, developer-soluble bottom anti-reflective coatings may also be partially crosslinked, thermoset materials that retain enough acid functionalities to still be soluble in base developer. Photosensitive bottom anti-reflective coatings have acid-labile crosslinks that are activated by photoacid generators. Other crosslinked photosensitive bottom anti-reflective coatings are known, but the nature of the crosslinking and the source of developer solubility is unclear. Other photosensitive bottom anti-reflective coatings behave more like photoresists in that dissolution in base is accomplished primarily by the cleavage of an acid-labile group that generates an acid unit in the polymer.
Previous photosensitive, developer-soluble, bottom anti-reflective coatings contain an acrylate terpolymer that contains a chromophore, a crosslinking unit, and an acid-labile group. These terpolymers offer good performance at larger critical dimensions (CDs), but resolution requirements have increased and this chemistry is not capable of achieving the necessary resolution of the smaller features. The molecular weight of the terpolymers has also become an issue since it is more difficult to dissolve and then completely remove the large molecules in alkaline developer.
Thus, there remains a need in the art for improved materials to formulate bottom anti-reflective coatings.